Dean Smith has been sacked as Norwich City head coach after a run of just three wins in 13 Championship matches.
Assistant manager Craig Shakespeare and first-team coach Liam Bramley have also left Carrow Road.
Steve Weaver and Allan Russell have taken caretaker charge of the team.
“As the club continues to work towards its on-field objectives this season, the board believe that it is the right time to make this transition,” Norwich said in a statement.
“The club will now work to identify and appoint a new head coach that is able to deliver both the level of performances required to challenge at the top end of the league whilst implementing a consistent style of play.”
Smith publicly questioned the attitude of some fans after the home defeat by Blackburn on 17 December and said playing away was better for his side.
“I think a lot of them have been waiting for this period to happen, or wanting it to – I don’t know,” he told BBC Radio Norfolk at the time.
Monday’s 2-1 defeat at Luton was a third defeat in four.
Canaries sporting director Stuart Webber added: “This was a tough decision, but one that we felt was necessary to give ourselves the best possible chance of achieving our objective of promotion to the Premier League this season.
“With just under half of the season remaining and three consecutive home games on the horizon we now have a real opportunity to build some forward and positive momentum, both on and off the pitch.”
The Canaries had been top of the table on 1 October but are now fifth and 12 points off the top two.
Smith was appointed as Daniel Farke’s successor in November 2021 but was unable to save them from relegation back to the Championship last season.
Farke won the second-tier title twice during his four and a half years at the helm, but on each occasion they only lasted a single campaign in the Premier League.
Smith began his managerial career at Walsall before moving on to Brentford and then Aston Villa.
He guided Villa to promotion from the Championship in 2019 and they reached the Carabao Cup final the following year.
The former defender was sacked following five successive Premier League defeats at the start of the 2021-22 season, only to take the Norwich job eight days later.